They way I usually break it down is asking what matters to you the most.

Beaver Builder is super reliable, you can count on it. It is primarily developer-centric and they cater to developers and agencies. But it's not design-centric so you will really need to buy and add on plugin like Ultimate Add-ons or use custom CSS to get a modern design.

Elementor is super aggressive in developing the plugin and in the past, there would be some minor update issues people would experience. They have become much better at releasing update over the last 6 months. Elementor is design-centric and produces beautiful modern designs. Also, there are less additional things to buy. A perfect example is the form builder in the Pro version, you don't get that kinda stuff with Beaver Builder.